1. Field of the Invention
The invention relates to a method of manufacturing polyalkyl methacrylate macromonomers, and use of same in the manufacture of comb polymers.
2. Description of the Background
Macromonomers are defined as polymers with a polymerizable, in particular radically polymerizable, end group, and have a molecular weight in the range 500-100,000, particularly in the range 2,000-50,000.
The manufacture of macromonomers is described at length in the literature (Rempp, P. F., and Franta, E., 1984 Adv. Polym. Sci., 58, 1; Albrecht, K., and Wunderlich, W., 1986 Angew. Makromol. Chem., 145/146, 89-100; Mark, H., et al., 1987, "Encyclopedia of Polymer Science & Technology", 2nd Ed., Vol. 9, pub. J. Wiley & Sons, 195-204; Rempp, P., Franta, E., Masson, P., and Lutz, P., 1986 Progr. Colloid & Polymer Sci., 72, 112-118; Rempp, P., et al., 1982 Makromol. Chem. Rapid Commun. 3, 499-504; Corner, T., 1984, "Advances in Polymer Science", No. 62, 95-144; Rempp, Paul F., and Franta, Emile, 1984, "Advances in Polymer Science", No. 58, 1-50; Gnanou, Yves, and Lutz, Pierre, 1989 Makromol. Chem., 190, 577-588; Tsukahara, Y., et al., 1989 Macromolecules, 22, 1546-1552; Tsukahara, Y., et al., 1989 Polym. J., 21, 377-391; and Ger. Pat. 2,723,905.
It is well known that macromonomers may be obtained via anionic and cationic "living polymerization", and via radical polymerization, by which the polymerizable end group is provided by means of initiation or chain cleavage, with or without subsequent chemical reaction.
Another interesting proposal for synthesizing macromonomers is provided by the method of "group transfer polymerization" (GTP) (see Mark, H. F., et al., 1987, "Encyclopedia of Polymer Science and Technology", 2nd Ed., Vol. 7, pub. J. Wiley & Sons, 580-588). Molecular weight is determined by gel permeation chromatography (see Mark, H. F., et al., ibid., Vol. 10, 1-19).
The glass transition temperature Tg is determined as described by Turi, E. A., 1981, "Thermal Characterization of Polymeric Materials", pub. Academic Press, New York; and/or Vieweg-Esser, 1975, "Kunststoff-Handbuch: Vol. IX, Polymethacrylate", pub. Carl Hanser Verlag, 333-340.
In Ger. OS 39 02 653, elastomers based on acrylates are described which are comprised of at least 40 wt. % and as much as 100 wt. % of one or more copolymers having a molecular weight &gt;50,000 Dalton, which copolymers are comprised of:
acrylate monomer units, in the amount of 50-95 wt. %; and
macromonomers, comprising a vinyl group and thus covalently bonded, which macromonomers are comprised of a polyvinyl unit which is chosen from the group of acrylates and methacrylates and (possibly substituted) styrenes. The macromonomers have a glass transition temperature .gtoreq.60.degree. C. and molecular weight of 500-100,000 Dalton.
A method of manufacturing comb polymers is described in Eur. OS 357,036. Also, graft copolymers with a comb structure and a very narrow molecular weight distribution of the monomers are described in Ger. Pat. 2,723,905.
As a rule, the manufacturing methods for macromonomers disclosed in the art lead, by plausible chemical mechanisms, primarily to products having reactive and/or activatable groups, which one may be able to modify chemically with the use of customary organic reactions, to produce the desired macromonomers. The available range of variations is determined primarily by the nature of the reactive and/or activatable groups, but also to a certain extent by the nature of the monomer units in the structure in which the monomer units are combined. The OH group, for example, can function as such a reactive group. It can be converted to a terminal monomer function by interaction with suitable acylating agents which contain polymerizable units, e.g. such agents as an isocyanate-substituted (meth)acrylic acid alkyl ester, or (meth)acrylic acid anhydride.
The acylating systems are relatively reactive, as is known from synthetic organic chemistry, and as a rule such regulated reactions require careful control as they proceed, generally in inert media; and even with such control measures side reactions are a possibility. A need therefore continues to exist for a method of preparing macromonomers under mild conditions and in improved yield.